Powered air breathing apparatus

ABSTRACT

A safety breathing apparatus has a sensor for measuring the difference in pressure between two point 1a, 1b in the gas delivered to a head unit 9. The sensor is used to measure the difference in the pressure of the gas supplied through the apparatus between the two points in the gas flow, and the pressure difference is then used to calculate the gas flow rate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/893,981 filed Feb. 12, 2018, allowed, which is a continuation of U.S.application Ser. No. 15/178,717, filed Jun. 10, 2016, which is acontinuation of U.S. application Ser. No. 13/521,024, filed Jun. 17,2013, now U.S. Pat. No. 9,387,299, which is a 371 of PCT/GB2010/051803,filed Oct. 27, 2010, which claims the benefit of GB applications0919211.3, filed Nov. 2, 2009, 0919277.4, filed Nov. 3, 2009 and1005293.4, filed Mar. 29, 2010, the disclosure of each of which isincorporated by reference in their entirety herein.

The present invention relates to improvement to powered air filteringdevices incorporating a helmet, mask or hood with particulate, gas orcombination filters for respiratory protection.

It has been recognized that it is advantageous to monitor and measurethe flow rate of air into a powered air respirator. This is becausemonitoring of the flow rate enables checks to be made to ensure that thefilter flow rate capability is not exceeded, thus ensuring that thefilter effectively filters all contaminants from the breathable airdelivered to the wearer. Furthermore, the air delivery control systemcan use a closed loop flow measurement system maintain a given flow rateto the user irrespective of changes in conditions such as changes in thefilter resistance or resistance of different headtop's or mask's worn bythe user; changes in ambient air pressure resulting from, for example,variations in altitude and the like. Similarly, an active system can usethe closed loop flow rate control to automatically compensate for theeffects of breathing that constantly vary the load on the breathing airdelivery fan assembly.

Modern respirators typically have a wide selection of accessories in theform of filter types, varying design of headtop or mask for differentapplications etc., and this gives rise to issues with maintaining agiven flow rate across any combination of accessories. The atmosphereis, by its very nature, compressible, and thus as flow rates increase ina powered air respirator, the air compresses and a nonlinearrelationship exists for flow rate and impeller speed. The flowresistance of a particular filter can also vary through its life asairborne particles are drawn into and retained on the filter medium,interfering with the movement of air therethrough and thus constantlyincreasing resistance through the filter life. Furthermore, the mere actof the user breathing causes variations in the load on the motor causingfluctuations in the flow rate. As the user breathes in, air is drawnthrough the filter, assisting the motor in supplying air and thereforeeffectively reducing the load. On the other hand, as the user breathesout, air flow is inhibited, even when a non-return valve is used,thereby increasing the load on the motor.

It is relatively easy to monitor the speed of the impeller duringoperation of the apparatus, and it has been suggested to use this tocalculate the flow rate. However, the natural efficiency of a fan designvaries with different loads placed on it by varying resistances on theair inlet side and on the loads on the air outlet side. As a result, theimpellor speed has no direct correlation to the flow rate.

Despite this issue with correlation between impellor speed and flowrate, for simple devices, such as a face mask with a built-in fan and alimited choice of filter/s, it has been found that a very goodapproximation of flow rate can be made by comparing motor speed andmotor load to create an algorithm of motor speed and load to estimateflow rate. It has also been known in the art to extend this approach tomore complicated systems, but has meant that for a given filter or headtop, the flow rate supplied by the respirator would be nearly constantbut different for each combination. This approach also suffers from thedrawback that it does not cater for changes resulting from variations inaltitude (motor speed will increase as the density of the atmospheredecreases). In some models, these drawbacks can be alleviated by varyingthe number of filters that can be fitted in an attempt to reduce some ofthe filter resistance loading—as more filters are fitted, the filterresistance becomes lower and a balancing act commences on the number offilters to level out the inlet load on the respirator.

Another known approach is to increase all the lower load filters to theequivalent highest load filters thereby equalizing the input load. Theadded complication to all this is that as the resistance changes overthe life of the filter, the load increases complicating the load andspeed algorithm. Another approach which has been proposed is tocalibrate the device using a rotameter, which is primarily a mass flowmeter and thus varies with humidity and altitude effects on density.

Thus, it can be seen that prior art approaches have generallyconcentrated on approximation methods for flow rate and these havegenerally been found to be acceptable. However, as a result of filtersgetting more technical for different contamination challenges, a desireto maintain a flow rate regardless of the initial filter resistance andvariations in filter resistance through its operating life, and a desirefor different headtops to suit different applications, theseapproximation methods are now becoming insufficient.

Furthermore, analysis of the air within a typical powered air breathingapparatus assembly has shown that turbulence exists in the respiratorassembly at flow rates that are required for breathing. This complicatesany generally acceptable way of measuring airflow without the use oflaminar air control system in place that causes a heavy load on thesystem either causing flow rates to be decreased and/or battery life ofbattery powered respirators to be reduced significantly.

According to the present invention there is provided a method ofmeasuring the flow rate of gas supply in safety breathing apparatuscomprising the steps of measuring the difference in the pressure of thegas supplied through the apparatus between at least two different pointsin the gas flow, and using said pressure difference to calculate the gasflow rate.

The present invention further provides a safety breathing apparatushaving means for measuring the difference in pressure of gas beingdelivered by the apparatus between at least two different points in thegas flow, whereby the gas flow rate can be calculated from said pressuredifferential.

The apparatus and method in accordance with the invention has theadvantage that by measuring pressure and using the differential tocalculate the flow rate of gas through the apparatus, a much moreaccurate figure for the flow rate is obtained as compared with prior artsystems without imposing a significant load on the air supply unit whichwould result in an increase in power requirements.

The pressure difference between the at least two points may be measureddirectly using a pressure differential gauge, such as by means of adiaphragm to opposing sides of which the pressure at each of the twopoints is supplied, deflection of the diaphragm measuring the pressuredifferential. Alternatively, the pressure may be directly measured ateach point and the pressure differential between the points may then becalculated

Preferably, a constriction is provided in the gas flow path, thepressure measurements being taken at the entry to and near the tightestpart of the constriction. This has the advantage that the pressuredifferential between the two measurement points is increased, therebyreducing the pressure sensor sensitivity necessary to achieve accuratemeasurement of the flow rate. In particular, the constriction is formedby a plate orifice, a shaped nozzle and a venturi tube.

In a particularly preferred embodiment of the invention, a DALL tube isused to create the orifice. This has the advantage that it reduces theenergy losses through the constriction considerably, which is importanton a battery powered device where the operating life could be seriouslyimpaired. In a further development of the present invention, pressurefluctuations caused by turbulent flow in the system are minimized byintroducing dampening/filtering in the form of a mechanical filter todampen the fluctuations although electrical filtering could also be usedto average out spikes in the pressure differential measurement system.

Advantageously, a closed loop system is used to alter the motor speedbased on the flow rate measurement to adjust the flow rate to reach ormaintain the target value.

Modem safety legislation sets various stringent servicing, testing anduse requirements for breathing apparatus in view of the potentiallylife-threatening implications of the failure of such equipment. It isimportant, for example, that a user only use equipment that he istrained to operate and that the correct equipment is used for thecorrect environment (use of a wrong filter, for example, can result inthe wearer being exposed to harmful contaminants even though he iswearing the equipment correctly). Similarly, all equipment must beregularly serviced and tested to ensure it is operating properly.

Conventionally, monitoring of such requirements has been carried outmanually—manual records being kept of the use time of equipment so as toenable service timetables to be calculated, and individual user checksbeing made m relation to equipment qualification/currency and correctapplication. Initiation Warranty, for example, is generally based onmanufacturing date or by the user logging the purchase with themanufacturing company. Such manual systems are, however, subject toinaccuracies, etc. which can lead to servicing being carried outun-necessarily early or delayed causing possible health risk to users.

There is accordingly a need for an improved system which preventsoperators using equipment they have not be trained to use or usingincorrect equipment for the hazardous area they are in, and to provideaccountability logging to ensure the product has been used appropriatelyin a hazardous environment. It is also an aim to provide a system whichensures that safety critical visual inspections and services are carriedout at due times, and that data logs prove the operator has carried outthose tasks. There is also a need to overcome Warranty Initiation delaysinherent from manufacturing date to the user receiving the equipment, byproviding an accurate record of when product was first used. Byproviding a very short delay time of say one hour to allow fordemonstration of the product, the warranty can start after the definedrun time delay.

Accordingly, the present invention further provides breathing apparatushaving interchangeable components, each component having anidentification means associated with it on which provides informationunique to said component, the apparatus comprising a controller having areader for reading the identification means of the or each componentattached to the apparatus so as to identify said components.

Breathing apparatus in accordance with the invention has the advantagethat, by reading information relating to each component removablyattached to the apparatus, the controller is able to carry out checkssuch as compatibility of different components, service history or thelike, and alert the use in the case that a problem is identified.

Preferably, the controller further includes a reader for reading asecond identification means which provides information associated withthe equipment user, the controller reading information from the or eachfirst identification means and the second identification means, andchecking for validity of the user to operate the equipment.

The identification means may carry a simple identification code uniqueto each device and or user, the controller being connected to a databasewhich stores data related to users and devices and using theidentification codes to look up the required data from the database.Each identification means may then be a barcode or the like, or may bean electronic storage means such as an RFID tag.

Each electronic storage means may be a wired storage medium whichrequires a direct connection with the reader for the reader to read datatherefrom or may be a wireless medium such as an RFID chip. Eachelectronic storage means may store a simple ID tag which links to datastored in a central database or may store the full set of data relativeto the component or user with which it is associated. In that case, theelectronic storage means preferably has a write capability by means ofwhich the controller is able to write information back to the storagemeans to enable an update of the data relating to the device with whichit is associated. For example, the storage means may take the form of orat least include a flash memory device.

The second identification means is preferably a Tally Key/RFID chipwhich stores all information relating to the user with which it isassociated. In one embodiment, the chip is mounted a coin type disk (inthis application, but could also be a card or similar). The breathingapparatus then includes a mount for receiving the chip and securingmounting it on the apparatus. In particular, the mount is advantageouslyprovided on a blower unit, the blower unit being inoperable until a chiphas been mounted in place. The tally key is advantageously programmedwith the information relating to permitted equipment types for the user,filter types allowed to be used, flow rate adjustment capability,pre-warning times and other suitable parameters. This tally key thenbecomes “persona}’ and can be moved from one product to another toensure operating parameters remain constant for the user.

Each first identification means advantageously stores operationinformation for the device with which it is associated, such asService/Inspection Status using a real-time clock inside the controlleror accessing real time clock from an external source. In this way,actual usage time can be used to identify when service and inspection isrequired. Each unit can be programmed to have visual safety inspectionsand services as required by the end user and or the manufacturer, atthese preset periods, a warning will warn the user or prevent the userfrom further use of the product until the inspection or service has beencarried out. Some allowances are built in to ensure that the productdoes not stop during use. For visual inspections by the user, the userwill need to confirm the visual inspection has been carried out and thesystem will log the user from the tally key and record the date, timeand user who carried out the visual inspection. Services will be done byan approved service department who will log into the blower relevantinformation and clear the warning flag. Warranty Initiation Using thereal-time clock, when the product is run for longer than the presettime, the warranty will be initiated in the blower and logged providingan absolute time/date of first use to prevent arguments over warrantystart.

It has not hitherto been known to provide a Tally Key (RFID) system astaught in the invention. Service/Inspection Status This is generallycarried out by manual documentation Warranty Initiation Warranty isgenerally based on manufacturing date or by the user logging thepurchase with the manufacturing company.

Alarms are used to in breathing apparatus to bring to the attention of auser potentially life-threatening issues such as low battery life andthe like. The use of audible alarms is conventional in the art, but in awork environment with many users, it is often difficult to identify thesource of audible alarms and this can result in each user ignoring thealarm on the assumption that it actually relates to another user. Visualalarms have also been tried and can work, but part of the equipment canoften be located out of the line of sight of the user (the field of viewgenerally being reduced by the breathing mask itself). For example, aPAPR unit is generally carried on an operator's back and cannot beeasily seen, so that a visual alarm provided on such a unit would beunlikely to be noticed by the user and it would, instead, be necessaryto rely on surrounding user to inform the wearer of the alarm.

The present invention therefore further provides breathing equipmenthaving a control unit and an alarm operable by the control unit toattract the attention of a user, wherein the alarm is a vibration alarmwhich communicates with the user through touch.

Breathing equipment incorporating a vibration alarm in accordance withthe invention has the advantage that it came reliably gain the attentionof the user to a possible risk situation in a manner which avoids thepossibility of the alarm being overlooked, for example in noisyenvironments, or ignored because the user thinks it has originated fromequipment other than his own.

Various forms of vibration alarm suitable for application to theinvention are known in the art-for example a weight eccentricallymounted on a motor shaft which is rotated to activate the alarm.However, the exact form of the vibration alarm is not important to theinvention.

The wide range of different applications and environments in whichmodern safety breathing apparatus is used necessitates modular typesystems in which different components can be connected to meet the userequirements of an environment. Most commonly, a range of differentfilters will be available for each mask to enable a generic mask to beused in different environments having different filter requirements andalso to enable a worn-out filter to be replaced. Prior art systemtypically uses a thread based or bayonet type system for attaching afilter and rely on frictional engagement when the thread or bayonet isfully engaged to retain the filter and prevent it being accidentallyremoved or loosened to an extent which could result in contaminated airmaking its way to the user. It has been known to use a compliant latchbased locking system, which latch is urged out of the way as the filteris screwed into place and then latches back in when the filter is fullyinserted. However, this system is still a fully rotation basedsystem—removal of the filter still only requires counter rotationalmovement of the filter, albeit with an increased initial forcesufficient to move the latch outwards to release the filter to unscrew.

According to the present invention there is provided a system forreleasably attaching a filter to breathing apparatus comprisingcomplementary male and female rotatably connecting coupling partsprovided on the filter and breathing apparatus, and an interlockprovided on at least one of the filter and the breathing apparatus, theinterlock being moveable between a retracted position in which it iswithdrawn from the coupling parts so as to allow rotation therebetween,and an engaged position in which it extends between the coupling partsso as to prevent relative rotation therebetween.

According to a further aspect of this part of the invention there isprovided a filter having one part of a male and female rotationalcoupling formed thereon, and further having one part of an interlocksystem, which, in use, cooperates with a complementary part of aninterlock system provided on a piece of breathing apparatus to preventrelative rotation between the filter and the breathing apparatus.

A still further aspect of this part of the invention provides a piece ofbreathing apparatus having one part of a male and female rotationalcoupling formed thereon, and further having one part of an interlocksystem, which, in use, cooperates with a complementary part of aninterlock system provided on a filter to prevent relative rotationbetween the filter and the breathing apparatus.

The system of this part of the invention has the advantage that theinterlock provides a positive and active lock between the filter and thebreathing apparatus which requires additional manual actuation by a userbefore the filter can be rotated for removal from the breathingapparatus, thereby preventing accidental loosening or removal of thefilter. The user has a definite indication that the filter is locked inplace.

The rotational coupling may be a thread coupling or a bayonet typecoupling, and is preferably configured with the female part of thecoupling being provided in the breathing apparatus and the male part onthe filter. It will, however, be understood that the reverseconfiguration is also possible, i.e. with the male part being providedon the breathing apparatus.

The interlock system preferably includes biasing means which biases oneof the parts of the interlock system into the engaged position, said onepart being moveable against the load of the biasing means into theretracted position in order to allow rotation between the filter and thebreathing apparatus. In a particularly preferred embodiment, theinterlock system comprises a peg mounted in one of the filter and thebreathing apparatus (preferably in the breathing apparatus) so as to beradially movable between the retracted and extended positions, and anopening in the other of the other of the filter and the breathingapparatus size to receive the peg, opening aligning with the pin whenthe filter is fully engaged with the breathing apparatus so as to allowthe pin to extend into the opening and thereby prevent further rotationof the filter relative to the breathing apparatus in either direction.Alternatively, the interlock could take the form of an axially moveablepin which is engageable between a pair of keyways provided in thecoupling parts so as to prevent rotation therebetween.

Preferably breathing apparatus to which the filter connects is a facemask or a blower unit.

In a positive pressure or sealed mask breathing system, a hose is usedto connect the air blow (PAPR blower) to the intake port of the masksfor delivering the air to the mask. It is important that the hoseconnection at either end is not pulled as this could result in the hosebecoming disconnected, allowing contaminated air to pass to the wearer.Movement of the wearer's head and torso during use can change thedistance between the mask and the blower, which, if the hose is not longenough, could result in tension being applied to the connections.Equally, variations in the size of the user will vary the normaldistance between the mask and the blower. Since it is usual to supply astandard-length hose for all users, that length must be chosen toaccommodate these variations in distance between mask and blower and thehoses are therefore generally on the longer side. This has the problem,however, that there will generally be some excess slack in the hosewhich will cause it to protrude from the body, providing a snagginghazard.

According to a further aspect of the present invention there is providedbreathing apparatus comprising breathing air supply means, a breathingmask, and an air delivery hose extending between the air supply meansand the breathing mask, the air delivery hose is a stretch hose, that isone which is extendable from a collapsed length to an extended length,the hose including biasing means which biases to its collapsed length.

A breathing apparatus in accordance with the invention has the advantagethat the stretch hose allows a naturally short hose to be used whichavoids excess length which could form into loops and present a snaggingrisk, whilst allowing the hose to extend to accommodate changes in thedistance between the mask and the air supply, such as through movementsof the head or the body or physical size of the user.

The strength of the biasing means should be sufficient to ensure thatthe hose promptly and reliably retracts to its collapsed length whentension is not applied thereto, but should not be so high to makestretching of the hose difficult or uncomfortable to the user or applytoo great a force on the connections on either end of the hose.

The form of the stretch hose itself is not important as long as the hoseis sufficient robust to ensure integrity of the breathing air suppliedthereby is maintained. Any conventional design for such a hose may beused, such as a hose which has a helically wound wire extendingtherealong which provides the biasing force which urges the hose to itscollapsed length. The hose material itself may then be stretchable toallow an increase in the length of the hose or may be flexible to allowthe material of the hose to fold on itself as the hose retracts to itscollapsed length.

As the hose extends, it has a natural tendency to twist, which can causecausing kinks to appear, risking damage to the hose and also restrictingthe flow of air through the hose to the mask. Preferably, therefore, atleast one of the ends of the hose is connected to its associated part bymeans of a rotatable coupling, that is one which allows the end of thehose to twist relative to the part to which it is connected whilstmaintaining a secure, air connection.

As described above, modem breathing apparatus is generally modular inform so as to enable a range of different components such as filters tobe provided for use with the core system.

Typically, the filters are removably attached to the system, such as theblower, by means of a threaded or bayonet coupling. This coupling pointpresents a potential point of ingress of contaminants into the airsupply and a seal is therefore generally provided on the bottom face ofthe thread or bayonet fitting in order to isolate the air supply frompossible contamination during use. However, the main body of the threador shaft of the bayonet fitting could still potentially be exposed tocontaminated air during use by a hazardous environment contamination canwork its way down the thread or bayonet. Whilst this is not a problemduring use when the filter is fitted as the contaminant will not be ableto get past the filter into the air supply, when removing the filter,there is a risk that contaminants may have been deposited on the surfaceof a region of the filter coupling which engages in the blower. Suchcontaminants may then be dislodged from the surface of the filtercoupling during removal of the filter, dropping into the blower bodypast the filter and compromising the air supply when the equipment isnext used.

The present invention therefore further provides a filter couplingarrangement comprising a filter having one of a complimentary elongatedmale and female coupling part, and a housing to which the filter isattachable, the housing having the other of the complimentary elongatedmale and female coupling part, said elongated male coupling part beingengageable in said female coupling part in order to secure the filter tothe housing, the male coupling part having a base, an end remote fromsaid base and coupling means provided between said base and said endwhich is engageable with complementary coupling means provided in thefemale coupling part, a first seal associated with the end of the malecoupling part such that, when the male and female coupling parts areconnected, an air tight seal is formed between the first end of the malecoupling part and the female coupling part, and a second seal associatedwith the base of the male coupling part such that, when connected, anair tight seal is formed between the base of male coupling part and thefemale coupling part, whereby the coupling means is isolated from thesurrounding atmosphere when the male and female coupling parts areconnected.

A filter coupling arrangement in accordance with the invention has theadvantage firstly that the provision of two seals gives a secondarylayer of protection against leakage through the connection into thefiltered air supply delivered to the user, and hence, for example,reduces the possibility of contamination due to a faulty seal.Additionally, however, the second seal, in isolating the connectingmeans from the surrounding atmosphere, prevent the possibility ofcontaminants being deposited on the surface of the connecting meanswhich could become detached during removal of the filter and causesecondary contamination upon next use.

The connecting means may be a thread, a bayonet coupling or otherwell-known form of coupling for securing a filter to a piece ofbreathing apparatus. Preferably, the seals are mounted on annular flangesurfaces formed at either end of the female coupling part, the femalecoupling part preferably being formed in the housing and the malecoupling part on the filter. The reverse configuration, both for theposition of the seals and the locations of the coupling parts is alsopossible and included within the teaching of the present application.

Battery powered respirators have an inherent problem of being unable tosupply peak air demand in high activity situations due to the powerrestrictions generally associated with battery powered devices.Additionally, when higher airflow is used to meet peak demand, thenature of the filters that decontaminate the air means that they have amore limited duration of operation. In order to solve this problem, itis known in the art to provide a self-contained breathing apparatus thatuses a cylinder of compressed air to supply the demand of the user. Thisapproach has the drawback, however, that, cylinder volume generallyrestricts operational time to less than one hour of operation and has aweight penalty for the user because of the weight of the cylinder. Thecost of the system is very high and special training is required due tothe risk of using high-pressure air. Specialist equipment is alsorequired to replenish the cylinders.

Another approach known in the art is to use an air line to supply air tothe user. This has the drawback, however, that the umbilical connectionwhich then permanently exists between the user and a fixed air supplyport restricts the user with respect to access to some areas due tobeing attached to an “umbilical cord” to the power source for the airsupply.

Conventional soft headtops generally use a non-breathing material thatactually acts as a reservoir—when the user breathes in, any demand notsatisfied by the blower is generally satisfied by the air in theheadtop, this can be easily seen in normal use as the headtop expandsand contracts during breath cycles. However, at very high volumebreathing rates this volume is insufficient and contaminated air canalso be pulled through from the outside by the loose fitting headtops.On full face masks, this reservoir does not exist and limits the amountof air available.

Accordingly, the present invention further provides breathing apparatuscomprising a blower unit, a breathing mask and a hose connecting theblower unit to the breathing mask, the blower unit being operable todeliver air to the breathing mask along the hose, and further comprisinga container located in-line between the blower unit and the breathingmask which acts as a reservoir from which air can be drawn by the userin higher demand situations.

The breathing apparatus in accordance with this further aspect of theinvention has the advantage that the buffering effect provided by thereservoir isolates the blower and filters from demand increases from theuser—the reservoir delivering the additional air required to meet thehigher demand. Although this will cause the volume of air in thereservoir to diminish, this will be topped up during the exhalationphase of the user's breathing cycle when air will still be delivered bythe blower but will not be drawn out by the user. Accordingly, thereservoir will act to meet a higher peak flow demand for a short periodof time during the inhalation part of the breath cycle.

The reservoir may be a flexible container or may be collapsible.Furthermore, it may be connected directly to the outlet of the blower,directly to the intake of the mask, or in-line in the delivery hose. Aone-way valve is preferably provided on the outlet end of the reservoirto prevent flow of air from the mask back into the reservoir. This willprevent back pressurization of the system which could still cause anincreased load on the blower and also will prevent exhaled air, whichwill have a higher carbon dioxide content, from being fed back into thereservoir for re-breathing by the user.

In order that the invention may be well understood, there will now bedescribed an embodiment thereof, given by way of example, referencebeing made to the accompanying drawings, in which:

FIG. 1 is a diagrammatic representation of a typical Powered AirPurified Respirator (PAPR) incorporating a flow rate monitoring systemaccording to the invention;

FIG. 2 a is a diagrammatic representation of a prior art PAPR having adirect hose connection between blower and headtop which is shown as ahood but could also be a mask;

FIG. 2 b is a diagrammatic representation of a system according toanother aspect of the invention in which a reservoir is located in linebetween the blower and the headtop which is shown as a hood but couldalso be a mask;

FIGS. 3 a and 4 a are rear and side elevations respectively of a priorart blower with a fixed hose arrangement;

FIGS. 3 b and 4 b are rear and side elevations respectively a blowerincorporating a stretch hose according to the present invention;

FIG. 5 a is a perspective view of a blower unit which forms part of theinvention;

FIG. 5 b is a section view through one of the filter ports of the blowershowing a sealing system which forms one aspect of the invention;

FIG. 5 c is a section end view of one of the filter ports of the blowerunit showing a positive lock system which forms one aspect of theinvention;

FIG. 5 d is an end view of a filter incorporate a recess for interfacewith the positive lock system shown in FIG. 5 c ; and

FIG. 6 is a diagrammatic representation of a dall tube which is usedwithin the system of the present invention.

Referring first to FIG. 1 , there is shown a Powered Air PurifiedRespirator (hereinafter PAPR) 7, of a type generally known in whichfilter(s) 10 are fixed to the PAPR 7 so as to filter air as it is drawninto the PAPR. The PAPR contains a motor 6 that drives an impellor in avolute 2 so as to suck air into the unit and deliver to a headtop/mask 9via a delivery tube or hose 8.

Located in line between the impeller and the headtop is a Dall tube 1which is utilized to monitor the flow rate of air supplied to theheadtop. The air supplied by the fan (impellor and volute 2) pullscontaminated air through the filter(s) 10 and pushes the breathable airthrough the Dall tube 1. The Dall tube 1 (shown in more detail in FIG. 6) has two pressure sensing points—a high pressure sensing point 1 a anda low-pressure sensing point 1 b, that connect to a pressuredifferential sensor which sends a signal to a signal conditioning block3. The pressure differential sensor may be composed of two pressuresensors 1 c, 1 d whose readings are then used to obtain a pressuredifference. Alternatively, a pressure differential sensor 1 e may beused which directly measures the pressure difference between the twopoints by provision of a fluid connection from the pressure sensingpoints to opposing sides of a diaphragm in a well-known manner.

In the illustrated embodiment, the signal conditioning block 3 ismounted on a control PCB 5 inside the PAPR 7. The Dall tube may becontained within the PAPR 7 or may be an external unit thereto asillustrated in FIG. 1 . Either analogue or digital based signaling maybe used to feed into the signal conditioning device. The pressure pickup points in the Dall tube 1 may also optionally have an inlinemechanical filtering device that reduces pressure fluctuations caused byturbulent flow in the Dall tube between the Dall tube and pressuredifferential sensor. Alternatively, a laminar flow device may be usedwithin the Dall tube to reduce the turbulence. A motor drive and speedcontrol 4 is also provided as the closed loop part of the system thatcontrols the motor speed to reach or maintain a targeted air flow.

The air flows through the impellor and volute 2, passes through the Dalltube 1 and proceeds via an air delivery tube 8 to be delivered asbreathable air to the user wearing the headtop 9. In an alternativeembodiment that is not illustrated, the system could be mounted inside aface mask that also has an integral fan assembly with the filter fitteddirectly to the mask or connected by a tube.

The use of the Dall tube 1 enables true air flow to be measured based onvolumetric flow rate that is critical as relating to filter capability.The system is also energy efficient system so as to minimize the impactto operating time on battery powered devices. Using this true air flowmeasurement, the true closed loop system controls actual air flow ratherthan calculated air flow and automatically compensates for differentresistances of different filters, headtops etc. The system alsocompensates for breathing pattern effects on the flow rate, and altitudecompensate is also built in.

It will, of course, be recognized that the pressure differential sensormay be used in other parts of the system, for example either side of thefilter, in the fan assembly or in the headtop. Two completely separatepressure sensors could also be used instead of a single pressuredifferential sensor.

The pressure sensors of the described system could also be used toprovide a breath responsive PAPR unit, as compared with prior art breathresponsive PAPR systems which typically use headtop or mask pressure toidentify the breathing cycle by identifying low pressure as thebreathing in cycle and the high pressure as the breathing out cycle.

The delivery tube/hose 8 takes the form of a stretch hose, asillustrated in FIGS. 3 b and 4 b , that is one which is biased into ashortened retracted length and which is extendable from said retractedlength against a retracting biasing load. In a well-known manner, thehose 8 is formed with a helical wire which extends the length of thehose and is wound so as to form a helical spring which has a naturalretracted shape, the spring force collapsing the material of the hoseonto itself to retract the hose whilst being easily extendable by simplepulling of the ends away from each other. It will, of course, berecognized that other configurations of retractable tube I hose may alsobe used.

The hose 8 is chosen to have a retracted length which is no longer thatthe shortest distance which can exist between the ports to which the twoends of the hose 8 are to be connected (in the embodiment of FIG. 1 ,the shortest distance between the port on the outlet of the Dall tube 1and the port on the headtop 9). As the distance between these two portsvaries during use, for example as a result of head or body movements,due to the equipment being used by a taller person or the like, the hoseextends to permit comfortable use by the wearer. The hose then retractsas the distance shortens so as to ensure that there is no slack in thehose which could form loops which might be prone to snagging asillustrated in FIGS. 3 a and 4 a . One or both ends of the hose is/areconnected to its associated port by means of a twist coupling whichallows free rotation of the hose end relative to the port. The form ofsuch a twist coupling is well known in the art and will not be describedin further detail here. This accommodates the natural tendency of thehose to twist as it extends I retracts, eliminating the risk of kinkingwhich could cause a snagging hazard.

Each filter, as shown in FIG. 5 a attached to a blower unit, isremovably connectable to a port of the blower unit in order to easilyenable filters to be replaced, either due to operational like havingexpired or because different filter characteristics are required. In theillustrated embodiment, as shown in more detail in FIGS. 5 b and 5 c ,each filter port 11 on the blower unit 7 has a female thread 12 formedon its inner cylindrical surface which complements a male thread formedon an engagement shaft of the filter 10 so as to enable the filter 10 tobe screw connected to the port 11. The filter port furthermore includesa radially extending locking peg 13 which locates in a radial aperture14 formed in the inner cylindrical surface of each filter port 11.Biasing means such as a compression spring 15 cooperates with thelocking peg 13 to urge it radially inwards such that it over laps thefemale thread 21 and forms and obstruction therein. In particular, inthe illustrated embodiment, the locking peg 13 is carried on a floatingring 13 a that is urged by the action of the spring 15 into a firstposition in which the peg 13 is moved radially inwardly. By moving thering 13 a against the load of the biasing spring 15, the locking peg 13is movable radially outwardly against the biasing load of the biasingmeans, through operation of a release lever accessible to a user on theexterior of the blower unit, so as to withdraw it from the female threadand thereby remove the obstruction.

The engagement shaft of each filter 10 has a recess 16 formed thereinextending from the threaded outer surface and shape to receive thelocking peg 13.

In order to fit a filter to the port, the male thread on the filter isaligned with the female thread 12 on the port 11 and the screw screwedtogether. When the leading edge of the male thread reaches the lockingpeg 13, the tapered formed of the start of the thread develops a cammingaction with the end of the peg 13, pressing it and hence the ring 13 aoutwards against the load of the biasing means into a withdrawn positionin which the peg 13 no longer obstructs the female thread and the filter10 and be further screwed into the port. It will be recognized thatinstead of the pin automatically being moved to a withdrawn position asthe filter is screwed into the port, manual withdraw by the user byoperation of the release lever may instead be necessary to enable thefilter to be fully screwed into the port.

The recess 16 formed in the engagement shaft of the filter 10 isposition so that it aligned both axially and circumferentially with thelocking pin 13 when the filter is fully engaged in the port 11, allowingthe pin 13 to snap inwards into the recess under the force of thebiasing means and hence locking the filter against further rotationalmovement relative to the port 11, either inwards or outwards. In thisway, accidental removal or loosening of the filter, which could allowcontaminated air to leak through the threads and into the air suppliedto the use, is prevented.

In order to remove the filter, the user operates the release lever tomanually move the ring 13 a against the load of the spring 15 and hencewithdraw the locking peg from the recess 16 in the engagement shaft.Only with the peg 13 is moved to a fully withdrawn position will thefilter be released for rotation in order to unscrew the filter from theport. This system therefore offers a significant improvement in securityagainst accidental release as compared with prior art systems in whichlocking means merely required an increased initial torque to be appliedto the filter in order to release the locking means and enable thefilter to be unscrewed.

It will be understood that whilst the illustrated embodiment has athreaded coupling between the filter and the port, other forms ofcoupling may also be used within the scope of the invention, such as abayonet type rotational coupling, it being important merely thatpositive intervention is required by the wearer in order to withdraw thelocking peg before the filter can be released or loosened in the port.

It can also be seen from FIGS. 5 b and 5 c that the filter port 11 isprovided with a pair of seals in order to ensure there is an air tightconnection between the filter and the port. More particularly, a firstseal 21 is located on a face of a circumferential flange 22 formed atthe bottom of the port 11 as is conventional in the art, the end of theengagement shaft of the filter 5 tightening against the first seal 21 inorder to form a primary barrier against the ingress of contaminated airbetween the filter and the port and into the clean air passage withinthe blower unit. The drawback with systems which include just a singleseal at this location is that both the male and female threads willstill be exposed to a degree to contaminated air which can result incontaminated deposits being left thereon. As the filter is removed,these deposits can be dislodged and drop through the filter port andinto the air delivery chamber inside the blower, contaminating the airdelivered to the user on next use.

The present system therefore has a second seal 23 associated with eachport 11 mounted on an upwardly facing surface of the port located abovethe thread 12 formed in the port. The second seal 23 is formed as askirt seal which tapers outwardly away from the top of the seal port. Asa filter is engaged onto the port, the skirt seal engages with thebottom face of the filter as shown in FIG. 5 b . The secondary sealthereby isolates the thread of both the port and the filter from thecontaminated air, thereby eliminating the risk of secondarycontamination of the clean air delivered to the user.

The safety of the PAPR of the invention is further improved by means ofa controller which is able to monitor the various components which areattached to the system and confirm suitability for use, generally aswell as with each other and by any particular operator. The controlleris also able to monitor and record operational time to enable userexposure information to be logged as well as equipment operating timesfor service purposes and the like.

This is achieved by means of the controller having a reader which isable to read a data tag associated with each component (filter, headtopetc.) connectable to the system for operational purposes. The data tagsfor the individual components may, for example, be RFID tags which areread wirelessly by the reader or may be some other form of ROM or flashmemory which is read by wireless means or by a direct connection, forexample using contacts on the components. In each case, the data tagwill be programmed with information relating to the component with whichit is associated, such as category (filter, headtop etc.), type (e.g.grade of filter), operating hours left before next service and the like.

Furthermore, each user will be equipped with a data tag in the form of atally key which carries information relating to that user. Again, thisis readable by the controller in a well-known manner, by direct contactor wirelessly. The tally key will be individual to the user and willstore information such as equipment which he/she is trained/authorizedto use, operating time on equipment, preferred setting for equipment andthe like.

In use, then, the various components will be connected together readyfor use and the system switched on. The controller will first of allcarry out a check to make sure that all components are properlyconnected by carrying out an initial polling of the data tags of thecomponents and also by some direct continuity check. The system willfurthermore carry out a check to ensure that all the components arecompatible with each other. For example, if incompatible filtersintended for different environments are connected to the ports of theblower, it could result in contaminated air being delivered to the useras in each environment only 1 of the filters would be providingeffective filtering. In the event that incompatibilities are identifiedby the controller, it will not allow the blower unit to start so as toprevent use, instead activating an alarm to signal a fault.

Prior to allowing use, the system will also require a user's tally keyto be logged with the controller. The controller will read the userspecific data from the tally key and perform an initial check to ensurethat the user is properly qualified/authorized to operate the variouscomponents which are connected to the unit and also to set any operatingparameters and/or restrictions which are applicable to that user (e.g.maximum time in a particular environment). Once all these checks havebeen completed successfully, the controller will allow operation of theequipment. Furthermore, the controller could start and then check asbefore and then alarm if something is wrong.

Once the equipment IS operational, the controller will then continue togather vanous component data during operation, recording the time duringwhich the equipment is operational, air flow rates etc., checking thedata against the settings prescribed for each component and/or theparticular user and activating an alarm in the event that any parameterfor either the equipment or the user is exceeded (e.g. maximum air flowrate for a particular filter is exceeded). The controller alsocontinuously monitors the status of the various components duringoperation of the system to ensure that they all remain properlyconnected throughout operation of the equipment.

The data gathered by the controller is recorded to keep a record of timeof use of each component as well as period of time during which theoperator has been using the equipment. The information may be recordedin a central database which is linked to the equipment/user by theunique ID carried on the memory device for each component or user.Alternatively, the data may be written back to the memory device of theassociated component or user for independent storage.

In summary, the electronic storage medium of the system can be utilisedto:

1) Ensure all filters are fitted and match before the product can start.

2) Check filters are not removed during use, and alarms if missing.

3) Enforce single use for filters.

4) Recognize headtops, similar features to filters.

Furthermore, the user unique second storage device/tally key can beutilized to:

1) Store user ID and product operating parameters/restrictions.

2) Log User data during use to identify the user and extent of use ofthe product, usage being written back to the chip, stored on the productor both (this is particularly useful for accountability reasons).

3) Store product operating parameters, so that should the user changethe product (gone for repair, service etc.), he does not have toreprogram operating parameters and can just use the next productstraight away.

4) Restrict Users to use only the types of equipment (filters, headtopsetc.) they have been trained and certified to use.

5) Record and check Service/Inspection Status.

6) Use a real-time clock to count down and warn of when a service orsafety inspection is required.

7) Ensure that unit is not used until a required service or inspectionis carried out.

8) Make/keep a log of safety visual inspections using the ID of theTally Key.

PAPR units generally have either a time duration warranty or motor lifewarranty. By using a real-time clock, the system of the invention canenable warranty automatically to start after a given run time, forexample one hour, the start date and time then recorded as the start ofthe warrant and also servicing periods (rather than from manufacturedate). Thus, the run time can be recorded ensuring either criterion ismet. This allows for products left on the shelf at distributors etc.Additionally, a user can be warned when warranty will expire or when itwas initiated.

As discussed above, the controller has various circumstances in which itmay need to activate and alarm to alert the user of an issue which needsattention. In the system of the invention this alarm includes avibration alarm which may take any of a number of forms which would bewell known to the skilled person in the art. For example, an electricmotor having a weight eccentrically mounted on its output shaft whichcauses the whole motor to vibrate as it rotates. The vibration alarm ispreferably located within the PAPR blower unit, which, typically beingcarried on the back of the user, will be detected particularly easily bythe user. However, other locations are also possible in otherembodiments. In an alarm situation arising, the controller with switchon the motor which will cause the whole blower unit to vibrate. Thiswill, then, be detected by the wearer regardless of whether he has sightof the unit. Equally, there is no possibility of mis-identifying analarm as being from another user's unit.

A further feature of the system of the invention is the use of a displaylocated in an area where it will be clearly visible to those surroundingand at a distance from the user. In particular, the display may bemounted in a prominent position on the blower unit or on the headtopitself or on a separate piece of equipment that could be body mounted.The controller is connected to the display either directly or wirelesslyand is able to control and change the background color depending on theenvironment for which the whole system has been set up for use (based,for example, on the type of filter etc.). For example, if one of thefilters connected to the blower is of a first grade suitable for amedium risk environment, even if the rest of the equipment is suitablefor higher risk environments, the system will change the backgroundcolor of the display to one corresponding to suitability for the mediumrisk environment only as the system is only safe to use up to thatlevel.

The use of this display system enables a supervisor easily to check thatthe correct equipment is being used in any particular environmentwithout necessarily having to be close to the user or even to enter theenvironment, the display giving clear visual guides if an operator is inthe wrong area or using the wrong equipment.

As shown in FIG. 2 b , in an embodiment variant, a reservoir 17 islocated in line between the PAPR and the head unit. Battery poweredrespirators have an inherent problem of being unable to supply peak airdemand in high activity situations due to the power restrictionsgenerally associated with battery powered devices. Additionally, whenhigher airflow is used to meet peak demand, the nature of the filtersthat decontaminate the air means that they have a more limited durationof operation. The reservoir 17 is used in the invention to meet peakdemand and generally to provide normal volumes of air so as to increasethe life of the filters.

The reservoir 17 stores air that is replenished during either anexhalation phase of the user's breathing cycle or lower demand phase.The reservoir 17 is then used to increase the air supply at peak demandwithout necessitating increasing the flow of air into the PAPR throughthe filters, thereby reducing power demands by the PAPR and alsoincreasing the life of filters which are not subjected to the higherflow rates.

The reservoir stores air at low pressure reservoir (the pressureachievable by the blower unit). The reservoir may be a light inflatable“bag” or a flexible light weight container, the volume of which ischosen to meeting high demand rates in line with the amount of air thatthe blower can provide—so for low flow rates from the blower thisreservoir need to be larger, but for higher flow rates it would besmaller.

A one-way valve 18 is located on the headtop end of the reservoir 17which ensures that exhaled air which has a higher carbon dioxide contentdoes not enter the reservoir, thereby preventing the user fromre-breathing exhaled air.

The invention claimed is:
 1. A breathing apparatus comprising: a blowerunit; multiple components removably coupled to the blower unit, thecomponents including at least a filter mounted to the blower unit and aface mask coupled to the blower unit via a hose, at least one of thecomponents having a component data tag affixed thereto, the componentdata tag storing component information associated with the at least oneof the components to which the component data tag is affixed, thecomponent information including at least one of a category of the atleast one of the components or a type of the at least one of thecomponents; and a controller communicatively coupled to the blower unit,the controller communicatively coupled to a reader that is configured toread the component information stored on the component data tag, thecontroller further configured to process user information that isassociated with a user of the breathing apparatus, wherein thecontroller is configured to process data of the component data tags andthe user information and to determine, based at least on the category orthe type the component, whether the user of the breathing apparatus isassociated with the blower unit, and, responsive to determining that theuser is not associated with the blower unit, the controller isconfigured to perform at least one operation.
 2. The breathing apparatusof claim 1, wherein, responsive to determining that the user is notauthorized to operate at least some of the components that are coupledto the blower unit, the controller is further configured to generate anoutput.
 3. The breathing apparatus of claim 2, wherein the output is avibration alarm disposed in the blower unit, the vibration alarmconfigured to vibrate upon activation to cause the blower unit tovibrate and be detected by a user that is carrying the blower unit. 4.The breathing apparatus of claim 1, wherein, responsive to determiningthat the user is associated with the blower unit, the controller isconfigured to allow the blower unit to be operable such that the blowerunit is able to be started by a user.
 5. The breathing apparatus ofclaim 1, wherein to perform the at least one operation is to generate anoutput.
 6. The breathing apparatus of claim 5, wherein the output is atleast one of a notification or logged data.
 7. The breathing apparatusof claim 1, wherein to perform the at least one operation is to notallow the blower unit to be operable.
 8. The breathing apparatus ofclaim 1, wherein the user information includes user authorizedequipment, and wherein to determine whether the user of the breathingapparatus is associated with the blower unit is to determine, using theuser information, whether the user of the breathing apparatus isauthorized to operate the blower unit.